This study was aimed to investigate the immunophenotypic characteristics of acute promyelocytic leukemia (APL). CD45/Side Scatter (SSC) gating strategy and multiparametric flow cytometry were used to determine immunophenotype of 143 patients with APL. The immunophenotypic features were compared between newly diagnosed APL patients and relapsed APL patients. 42 patients with HLA-DR(-) (non-APL AML, DR(-)AML) were randomly selected as controls. 31 out of 42 AML patients were CD34 negative, and their immunophenotypes were compared with those in newly diagnosed APL patients. The results showed that (1) CD34 and HLA-DR were both negative in 91.9% of newly diagnosed APL, while the positive rate of CD34 and HLA-DR elevated in relapsed cases (3.0% vs 37.5%, 3.9% vs 37.5%). The positive rate of CD34 in HLA-DR(-) AML group was higher than that in newly diagnosed APL group (23.4% vs 3.0%). The positive level of CD34 in newly diagnosed APL group was lower than that in HLA-DR(-) AML group; (2) the positive rate of CD33 in newly diagnosed APL group was higher than that in other groups (97.0% vs 75.0%, 83.3%, 83.9%), as well as the the positive level of CD33 (p < 0.05). (3) no lymphoid antigen other than CD2 was expressed in newly diagnosed APL group. The positive rate of CD7 was 9.5% in DR(-) AML group and 6.5% in CD34(-)/DR(-) AML group, both were higher than those of newly diagnosed APL group (p < 0.05). It is concluded that the immunophenotyping can provide proof to the rapid diagnosis of APL. For those patients with DR(-) AML, it may be helpful to identify APL depending on following features: low or negative CD34 expression, homogeneous and bright expression of CD33, no lymphoid antigens other than CD2, higher SSC.